By electronic label one understands, a set having at least one support, an antenna and an electronic chip. This set can include several antennas or several chips according to the requirements. One finds them in the form of a button, in chip cards and even in luggage labels. Thanks to their antennas, they can communicate with a remote reader. The antenna serves not only as a means of communication, but also to produce the necessary energy to feed the electronic chip.
Some of these labels do not include electronic chips but passive components such as resistors or fuses. They are used to identify objects, for example in an anti-theft application.
According to the embodiments, the antenna is fitted to the flexible support or directly engraved or cut on this same support.
There are a lot of chips, which differ because of their functionalities, for example certain ones allow only the reading of information while others allow memorization and modification of their memory. The latter are used among other reasons for electronic cash card applications, which obviously need, a read/write feature in order to modify the contents according to the consumption of the user.
Another important application field is identification of the objects. In fact, in an automatic manufacturing cycle, it is indispensable than the automaton knows exactly which component it is in front of. The tendency in this kind of use is to replace the “bar-code” labels by labels equipped with an electronic chip. This not only allows identification of the object but also inversely allows the object to remember the manufacturing steps that it has been through.
Nevertheless, the problem that this kind of using comes from the nature of the object. In fact, these labels work according to the principle of a link by a magnetic field, they are disturbed by the proximity of a metallic mass absorbing the waves that allow communication.
In order to overcome this drawback, it is necessary to bring the label reader nearer to a distance of some millimeters to restore the communication.
In certain applications, one easily imagines that this distance constraint can present major drawbacks for objects having an angular outline for example.
There are solutions in which such a label comprises an electric conductive layer. There is for example the case in the document U.S. Pat. No. 5,920,290 where one of the executions describes a set of an antenna and a conductive sheet to create a resonant circuit. The aim of such a sheet, whose structure can also be obtained as well by metal coating as by carbon supplying, shows that the aim and the means to achieve this are far from the object of the present application.
Other documents describe the use of a conductive layer inside an electronic label that makes the necessary tracks for the routing of electric signals. There is the case in document WO00/03354 that is about the manufacturing of a TAG by assembling different layers. No mention of a magnetic reflector function is present in relation to these conductive layers.
Document WO00/25263 describes a protection method of a transponder against discharges of static electricity. This protection is achieved with a sheet of semiconductor material placed on a section of the coil. With its structure, it forms a diode limiter between the turns of the coil. Otherwise said, this sheet constitutes a filter in charged to eliminate parasitic signals created by static discharge or electromagnetic disturbances which could harm the good work of the transponder. Such a semiconductor sheet cannot thus in any case be magneto reflective because its role is limited, on the contrary, to reducing or to absorbing undesirable electromagnetic signals. By the way, this document does not mention electromagnetic field reflection by a component of the transponder or possible problems caused by the support where this transponder would be applied.